Some nations of Europe have historically been a stumbling block for the advance of socialism. The Baltics, despite being liberated by the Soviets and allowed to retain their languages and identities, responded by sabotaging the Union and defecting to NATO.
Engels dealt with such entities by counting them as Volkerabfalle, or people which are counter-revolutionary by virtue of existence, and who should be absorbed by historically progressive cultures (in the case of the Baltics, Russian culture). I am inclined to agree, seeing their tendency towards fascism.
What do you think, comrades?
Situation is always changing. In 1848 Poles were revolutionaries, while Russian and Croats were reactionaries, but in 1918 roles reversed. Latvians in 1905 and 1917 fought for the revolution while after 90s they are pretty reactionary.